The purpose of the Joslin Animal Physiology Core is to provide technically advanced physiological evaluation of rodents for the study of diabetes, obesity, and their associated complications. The study of animal models is an integral part of Joslin Research, and DRC invesfigators maintain more than 10,000 mice and rats in the Joslin Animal Facility, and more than 7,000 mice offsite. Joslin DRC invesfigators have generated approximately 150 strains of genefically engineered mice during the last 15 years, the majority of which have been studied using the Animal Physiology Core. To better serve Joslin DRC investigators and enable outside users, a new facility for the Animal Physiology Core Laboratory will be built in 2012 within the Joslin. This new facility will consolidate services in one facility and expand services provided by the Core. Core services provided by the Animal Physiology Core include: Comprehensive Laboratory Monitoring Systems (CLAMS) for the measurement of in vivo energy expenditure, activity and fuel utilization; Dual Energy X-ray Absorptiometry (DEXA) for assessment of body composifion; blood pressure measurement by tail vein and telemetry; systemic blood perfusion studies using Laser Doppler Perfusion Imaging system (LDPI); and hypoxia and hyperoxia using an OxyCycler. New services that are proposed for the Animal Physiology Core include: IVIS Spectrum CT for in vivo animal imaging; diurnal incubator for studies of cold exposure; and rodent treadmill and wheel cages for studies of exercise. The Animal Physiology Core has consistently provided service to DRC investigators (approximately 14/year) and has been essenfial in the publicafion of multiple papers in high impact journals such as Cell Metabolism, the Journal of Clinical Investigation and Nature Medicine. Joslin support for the Animal Physiology Core has been substantial, with total cost for new and replacement instruments of $400,000 in the last three years. In addifion, Joslin has committed to build a new Animal Physiology Core facility and to purchase new equipment that will continue to keep Joslin animal-based research at the forefront of diabetes research.